(i) Field of the Invention:
This invention relates to a thick pearl luster dispersion and more particularly, to a thick pearl luster dispersion which is obtained by mixing large amounts of fatty acid glycol esters with a specific type of solvent, and heating and cooling the mixture to precipitate the resulting product as crystals whereby the dispersion becomes uniform in shape of crystals and low in viscosity with excellent high and low temperature stability.
(ii) Description of the Prior Art:
In order to enhance the commercial value of shampooes, rinses, hair-washing creams, liquid detergents and the like, it is the usual practice that these compositions are controlled to have pearl luster appearance. This practice has been realized, for example, by several techniques including mixing of powdered natural products such as mica, fish scales, bismuth oxychloride and the like and inorganic materials, and crystallization of polyvalent metal salts of higher fatty acids, and fatty acid glycol esters in these compositions.
Among these techniques, the currently, widely employed technique is a method using fatty acid glycol esters. In this method, materials which are solid at a normal temperature are added upon preparation of shampoo or the like and after heating and melting, are again cooled for recrystallization to impart pearl-like gloss thereto. Also, there are known methods such as disclosed in Japanese Patent Publication No. 47-804 and Japanese Laid-open Specification No. 5671021 in which fatty acid glycol esters are first molten and cooled to give a pearl luster dispersion and mixed with starting materials for shampoo or the like at a normal temperature.
The method of Japanese Patent Publication No. 47-804 makes use of fatty acid glycol esters and fatty acid monoalkylolamides in combination to give pearl luster. In this method, when a pearl luster of high concentration is prepared, its viscosity becomes abnormally high, involving disadvantages in handling on addition of the luster at a normal temperature for the preparation of shampoo or the like. Also, it takes a long time before uniform mixing with other ingredients.
The Japanese Laid-open Specification No. 56-71021 describes a method for preparing a pearl-like luster which comprises a fatty acid esters in high concentrations. However, this method involves the disadvantage that fatty acid glycol esters are scattered with respect to particle size of crystals with nonuniform shape of crystals, making it difficult to give a beautiful pearl luster appearance.